Diagnosing and Understanding OBD-II Connector Corrosion Overview

Written By Support Team

Corrosion of the OBD-II connector pins on telematics devices (e.g., Geotab GO devices) is an industry-wide hardware failure mode. Physical degradation occurs due to environmental factors, leading to intermittent electrical connectivity, signal instability, and device communication failures. This issue can occur even in vehicles that do not have active water leaks.Symptoms of Corrosion.

When examining a suspected unit, technicians should look for the following indicators:

  • Physical Evidence: Heavy green or blue oxidation on the OBD-II connector pins, which indicates water or moisture ingress.

  • Behavioral Indicators:

    • CAN Bus Communication Errors: Frequently observed as "burst events" (dozens of errors occurring within seconds).

    • Intermittent Connection: Repeated device drops, restarts, or false "device unplugged" events.

    • Signal Instability: Burst patterns are a strong indicator of an unstable physical connection as the device repeatedly attempts to reconnect to the vehicle network.

Root Causes of Moisture Ingress

"Dry" vehicle cabins are not hermetically sealed and remain susceptible to moisture. Potential pathways for oxidation include:

  • Condensation from Temperature Cycling: This is the most common cause. Cold nights followed by a warm cabin (or vice versa) cause moisture in the air to condense directly on the metal connector pins.

  • HVAC-Delivered Humidity: Heating and cooling systems circulate outside air, which may deposit moisture on the pins depending on vent placement.

  • External Contamination: Accidental introduction of liquids, such as windshield washer fluid, cleaning sprays, or beverage spills near the dashboard.

  • Prior Water Intrusion: Residual moisture from past windshield, door, or roof seal issues can persist within the cab environment.

Troubleshooting & Diagnosis

  1. Visual Inspection: Physically inspect the connector pins of the GO device. Look for distinct oxidation (green/blue discoloration).

  2. Log Analysis: Pull fault history from MyGeotab. Correlate device behavior with physical damage. High volumes of CAN bus communication errors clustered in short timeframes often correlate with thermal cycling windows (e.g., cold weather cycles).

Resolution Policy

  • Warranty/RMA Status: Devices exhibiting severe physical damage, such as connector pin oxidation, are typically considered damaged and are often ineligible for RMA replacement.

  • Corrective Action: Once corrosion is confirmed as the cause of failure, the recommended resolution is to order a replacement GO device.